Why do we prefer a convex mirror as a re | Class 10 Science Chapter Light - Reflection and Refraction, Light - Reflection and Refraction NCERT Solutions

When a 12 V battery is connected across an unknown resistor, there is a current of 2.5 mA in the circuit. Find the value of the resistance of the resistor.

Outline a project which aims to find the dominant coat colour in dogs.

Draw the structure for the following compounds.                

       (i)    Ethanoic acid             (ii)   Bromopentane*
       (iii)  Butanone                   (iv)   Hexanal.

*Are structural isomers possible for bromopentane?

A hot plate of an electric oven connected to a 220 V line has two resistance coils A and B, each of 24 Ω resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

How is the sex of the child determined in human beings?

(a)  What property do all elements in the same column of the Periodic Table as boron have in common?
(b)  What property do all elements in the same column of the Periodic Table as fluorine have in common?

Calculate the number of electrons constituting one coulomb of charge.

A man with blood group A marries a woman with blood group O and their daughter has blood group O. Is this information enough to tell you which of the traits – blood group A or O – is dominant? Why or why not?

What is an homologous series? Explain with an example.

Why is variation beneficial to the species but not necessarily for the individual?

Why is improper disposal of waste a curse to the environment?

Explain the following terms with one example each.

(a) Corrosion
(b) Rancidity

What are fossils? What do they tell us about the process of evolution?

Describe sexually transmitted diseases and mention the ways to prevent them.

Why is there a need to harness non-conventional sources of energy? Give two main reasons.

What are the advantages of sexual reproduction over asexual reproduction?

Reproduction is essentially a phenomenon that is not for survival of an individual but for the stability of a species. Justify.

How do auxins promote the growth of a tendril around a support?

How is the sex of a newborn determined in humans?

Describe the process of urine formation in kidneys.